Grinding roll chair



Dec. 28,1926. 1,612,502

. J. A. W. FICKENSCHER GRINDING ROLL CHAIR Filed Apl 27, 1926 1n verdor Patented Dec. 28, 1926.

UITED STATES PATENT FFICEe JOHANN ADAM WILHELM FIGKENSCH-ER, OF DRESDEN-BLASEVJITZ, GERMANY.

GRINDING ROLL CHAIR.

Application filed April 27, 1926, Serial No. 105,009, and in Germany December 27, 1924.

This invention relates to grinding mills and has for its object to produce a grinding mill having a number of passes or grinding gaps equal to the number of grinding rolls. According to the present invention a number of grinding rolls, not less than four, are arranged in series with each roll of the series in a position which enables it to coact with two other rolls of the series,so as to form a number of grinding gaps equal to the number of rolls, means being provided for positively rotating the rolls, each roll in the opposite direction to that of the rolls with which it coacts and with the peripheral speed of the second and each subsequent roll which precedes it.

The object of the invention is to provide a grinding roll chair of this type wherein the rolls cooperate, with successively increasing velocity, to form a number of grinding gaps equal to the number of rolls, and in which the material, is carried along by the more rapidly rotating roll, passes alternately to the interior and exterior of the annular series of rolls and is finally scraped on the last roll after being ground between it and the first roll. f

Owing to the rolls of the' rolling mechanism being arranged in such a way that their peripheries circumscribe a closed iig-Y ure, and to the number of rolls being an even number not less than four, the material to be ground is guided in a -sinuous line from one rolling gap to another all round the said closed figure. After it has been worked for the last time between the last roller and the first it is scraped olf from the last roll. In a manner which is known in connection with roll chairs of other kinds the relative speeds increase between each .co-operating pair of rolls from the inlet gap to the last grinding gap, as a result of which the feed ing forward of the material in the desired manner is ensured.

The arrangement according to the invention has the advantage that there are just as many roll gaps working as there are rolls, since the last roll in its turn co-operates with the first. IFIence, yas compared with the usual series arrangement, one roll is saved. Furthermore, however, there is also a substantial saving in sliding bearings and in adjusting devices, because in the case of four rolls two can be journalled in stationary bearings, and more than two in the case of a larger number of rolls, thereby cheapening the manufacture of the machine. Furthermore as compared with a roll chair having rolls arranged in series horizontally, the floor area required by the machine is diminished without thereby rendering 'the feeding of the material to be ground more difficult by having to supply it at a greater height, as vwould be necessary in the event of the rolls being superposed in a vertical or inclined row.

Figures l and 2 of the .accompanying` drawings show a grinding roll chair with four rolls, a, Y), c, and d, arranged in accordance with the present invention, to form four grinding gaps, LII, III, IV, through which the material being ground passes in succession. The driving of the rolls is effected by means of spur wheel gearing provided at the ends of the rolls on both sides of the machine, the gearing being so de signed that the speed of revolution of the rolls increases from a through o and c to d, F or example, a may make 20 revolutions per minute, Z9 40, c 8O and l 130, or other speeds of revolution may be selected in the same proportion. The directions of rotation correspond to the directions shown in the drawing by arrows. In the space located above the rolls a and Z9 and therefore outside theclosed figure I, II, III, IV a filling trough e is fitted. Against the periphery of the roll CZ, at a point within the closed ligure I, II, III, IV, there bears a scraper f. Two ofthe rolls, o and c for example, are journalled in stationary bearings, while the other two, I) and d, are adjustable in a f known manner by means Aofscrew spindles L and z' for the purpose of enabling the contact gaps to be narrowed or widened.

The material to be ground comes, in the filling trough e, into /contact with the two vrolls a and 7), which draw it through the gap I. The difference between the peripheral velocities of the rollers a and 5 gives rise to a relative slipping of the surfaces of these rolls at I, thereby imparting to the material its first grinding treatment. Since the angular velocity of the roll Z) is greater than that of the roll a, and since it is found by practical experience that the material being ground always remains adhering to the morel rapidly rotating' roll, the material is carried forward along the inner side of the roll Z), that is to say, the side facing the interior of the closed figures I, II, III, IV, to the gap II, wherev the same grinding takes place as at the gap I. In a similar manner the material is carried away upon the faster roll c,v but upon the outer side thereof, that is to say, the side remote trom the other rolls. On the roll c the material reaches the gap III, and is there treated again, after which it passes round the inner side ot the roll (l, and is linally carried to the gap IV between the rolls Z and a, where the fourth treatment takes place. In consequence ot the great difference between the peripheral velocities ot the. rolls a and d this stage ot the treatment is the most intensive. The scraping knife inally scrapes oit the ultimate product from the outer side of the roller al, and it collects in the receiver g. Hence, according to the invention, there are termed as many successive grinding gaps acting upon the material as there are rolls, so there is a saving of one roll as compared with the usual series arrangement ot rolls in the case ot roll chairs with progressive grinding oii the material in a plurality ot successive roll gaps.

It may happen under some circumstances that the material passing between the rolls a and is not completely removed by the roll b trom the roll ce. The material which remains adhering to the roll a would then pass directly to the last grinding gap, between the rolls a and d, and would thus only be ground twice instead of four times. This is obviated by a scraper arranged at m between the rolls and acting upon the roll a. What it scrapes off lalls on to the roll c and thus passes through the grinding gap II between and c and then through the two other grinding gaps, so 'that it also is ground t'our times.

Ihat I claim is l. In a grinding mill in combination, an even number ot grinding rolls not less than tour arranged in series with each roll of the series in a position for enabling it to coact with two other rolls of the series so as to form a number ot grinding gaps equal to the number of rolls, means tor positively rotating said rolls, each roll in the opposite direction to that oi the rolls with which it coacts and with the peripheral speed of the second and each subsequent roll greater than that of the roll that precedes it, means for supplying material to be ground to the grinding gap between the first and second rolls of the series, and means for removing ground material from the last roll.

2. In a grinding mill in combination, an even number ot rolls not less than 'iour arranged in series with each roll ot the Series in a position for enabling it to coact with two other rolls of the series so as to orm a number of grinding gaps equal to the number ot rolls, means tor displacing alternate rolls of the series for varying the widths ot said gaps two at a time, means 'tor positively rotating said rolls, each roll in the opposite direction to that of the rolls with which it coacts and with the peripheral speed of the second and each subsequent roll greater than that ot' the roll that precedes it, means for supplying material to be ground to the grinding gap between the irst and second rolls ot the series, and means for removing material from the last roll.

3. In a grinding mill in combination, an even number Vof rolls not less than tour arranged in series with each roll of the series in a position 'for enabling it to coact with two other rolls of the series so as to form a number ot grinding gaps equal to the num ber ot rolls, means tor displacing alternate rolls otl the series iior varying the widths ot said gaps two at a time, said means comprising slidable bearings tor the said alternate rolls, and means for adjusting the positions ot said slidable bearings, means :tor positively rotating the rolls, each roll in the opposite direction to that of the rolls with which it co-operates and with the .peripheral speed ot the second and Aeach subsequent roll greater than that of the roll that precedes it, means for sup lying material to be ground to the grinc ing gap between the irst and second rolls of the series, and means for removing ground material trom the last roll.

Il. In a grinding mill in combination, an even number or' rolls not less than tour arranged in series with each roll of lthe series in a position for enabling it to coact with two other rolls of the series so as toform a number of grinding gaps equal to the number ot rolls, means tor positively rotating said rolls, each roll in the opposite direction to that ot the rolls with which it co-operates and with the peripheral speed of the second and each subsequent roll greater than that ot the roll that precedes it, means tor supplying material to be ground to the grinding gap between the first and second rolls of the series, means tor preventing any material .trom adhering to the periphery of the first roll and passing directly to the last grinding gap after passing through the irst grinding gap, and means for removing ground material from the last roll.

5. In a grinding mill in combination, an even number of rolls not less than tour arranged in series with each roll of the series in a position for enabling it to coact with two other rolls oi' the series so as to form a` number of grinding gaps equal to the number ot' rolls, slidable bearings for alternate rolls of the series, screw spindles for adjusting the positions ot said slidable bearings to vary the widths of the grindinggaps, spur gears tor positively rotating said rolls, each roll in the opposite direction to that ot the rolls with which it coacts andwith the peripheral speed oit the second and each subsequent roll greater than that oi the roll that precedes it, means for supplying material to be ground to the grinding gap between the irst and second rolls of the series, a scraper for removing any material that may adhere to the periphery of the first roil and preventing it from passing to the last grinding gap after passing through the first grinding gap7 and a scraper for removing ground material from the last roll. 10

In testimony whereof I have signed my name to the specification.

JOHANN ADAM WILHELM FICKENSCHER. 

